This invention relates to heat traps in solar-to-thermal energy converters. extending
Various devices have been used in conjunction with solar energy absorbers to prevent loss by thermal radiation, convection, and conduction of the heat collected by the absorber. E.g., Buchberg et al., Performance Characteristics of Rectangular Honeycomb Solar-Thermal Converters, Solar Energy, Vol. 13, p. 193 (1971) describes a honeycomb structure between the absorber and a transparent window. The honeycomb cells are small enough to limit convection, and the honeycomb walls are thermally absorptive to limit radiation. Experimental work has been done modifying the honeycomb approach by using closely spaced parallel walls running perpendicular to the window to provide long narrow channels which limit losses in a manner similar to the honeycomb cells but which, if arranged with the channels extendng along the east-west travel direction of the sun, interfere less with transmission of the solar energy to the absorber. Additional windows, parallel to the outer window, have also been tried; these inhibit convection but have the disadvantage of seriously interfering with transmission by reflecting substantial light away from the absorber.